Biology

Water, pH, and Buffers

Hands-on labs, inc. Version 42-0136-00-01

Lab Report

PHOTOS – Include two digital photos with your lab report, either as separate attachments to an e-mail or paste into your document.

1. Photo #1 – Take a photo of the celery after it has been sitting for at least 4 hours.

Get close enough to see the results

2. Photo #2 – Take a photo of the HORIZONTAL needle observation.

Be sure you are close enough to see the needle and how it is relative to the water.

3. Photo #3 – Take a photo of your test results –

the layout of the commercial and homemade pH papers side by side

after dipping into each well. –It matches table #5

(This is the paper towel with the 12 numbers on it, with the papers beside the well #.)

Exercise 1: Water and its Unique Properties

Part I

Data Table 1: Needle Observations

Vertical:

Horizontal:

Part ii

Data Table 2: Paper Clips Needed to Break Surface Tension

Hypothesis:

Result:

Paper clips

Paper clips

Experiment

Water, ph, and Buffers

96

©Hands-On Labs, Inc.

www.LabPaq.com

Part iii

Data Table 3: Drops of Water

Hypothesis:

Result:

Questions for parts i, ii, iii

A. How did the experiment in Part I demonstrate surface tension? Use your experiment

observations when answering this question.

B. In Part I, when adding the needle to the water, which approach worked best to balance the

needle on the water—the vertical or horizontal placement? Explain your answer.

Part iV

Data Table 4: Part IV Observations

Observations:

Question for part IV

A. How did this activity demonstrate capillary action? Explain your answer using your experiment results and observations.

Exercise 3: Testing Common Household Materials

for pH Values

Observations

Data Table 5: pH Observations

Well

Plate

item tested

Commercial

pH strip

Homemade

pH strip

Color

pH

Color

pH

1

HCl

(hydrochloric acid)

2

NaOH

(sodium hydroxide)

3

Distilled water

4

Lemon juice

5

Orange juice

6

Coca cola

7

8

9

10

11

12

Data Table 6: Analysis of Results

Well plate

item tested

Acid/B ase/ Neutral?

Explanation:

1

HCl (hydrochloric acid)

2

NaOH (sodium hydroxide)

3

Distilled water

Questions:

A. Compare and contrast the results between the commercial and homemade pH test strips. Which test strips were more accurate? Explain your answer.

B. Why is the pH scale important in science? Give several examples of scientific applications.

C. What information about a chemical can be inferred from knowing its pH value?

D. If a chemical has a pH of 3, how could you change its pH value to be more basic?

Exercise 4: Buffers in a Living System

Observations

Data Table 7: pH Change of Buffered and Unbuffered Solutions

Unbuffered solution

Buffered solution

Initial pH

+ 3 drops HCl

+ 6 drops HCl

+ 9 drops HCl

+ 12 drops

HCl

+15 drops HCl

+18 drops HCl

Questions:

A. Analyze the results of your experiment. Did the buffer resist changes in the pH? Explain your

answer using your experiment results.

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Lab Report

PHOTOS

Include two digital photos with your lab report, either as separate attachments to an e

mail

or paste into your document.

1.

Photo #1

Take a photo of the

celery after it has been sitting for at least 4 hours.

Get close enough to see the results

2.

Photo #2

Take a photo of the HORIZONTAL needle observation.

Be sure you are close enough to see

the needle and how it is relative to the water.

3.

Photo #

3

Take a photo of your test results

the layout of the commercial and homemade pH papers side by side

after dipping into each well.

It matches table #5

(This is the paper towel with the 12

numbers on it, with the papers beside the well #.

)

E

x

e

r

cise 1:

W

a

t

er and its Unique P

r

operties

P

art

I

D

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t

a

T

able 1: Needle O

b

se

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tions

V

erti

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al:

Hori

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al:

P

art

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able 2:

P

aper Cli

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s Needed

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o B

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eak Sur

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ace

T

ension

Hypothesis:

R

esult:

P

aper

cli

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s

P

aper

cli

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s

Experiment

Water, ph, and Buffers

96 ©Hands-On Labs, Inc.

www.LabPaq.com

Water, pH, and Buffers

Hands-on labs, inc. Version 42-0136-00-01

Lab Report

PHOTOS – Include two digital photos with your lab report, either as separate attachments to an e-

mail or paste into your document.

1. Photo #1 – Take a photo of the celery after it has been sitting for at least 4 hours.

Get close enough to see the results

2. Photo #2 – Take a photo of the HORIZONTAL needle observation.

Be sure you are close enough to see the needle and how it is relative to the water.

3. Photo #3 – Take a photo of your test results –

the layout of the commercial and homemade pH papers side by side

after dipping into each well. –It matches table #5

(This is the paper towel with the 12 numbers on it, with the papers beside the well #.)

Exercise 1: Water and its Unique Properties

Part I

Data Table 1: Needle Observations

Vertical: Horizontal:

Part ii

Data Table 2: Paper Clips Needed to Break Surface Tension

Hypothesis: Result:

Paper clips

Paper clips

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